1840.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



25 



ANTIQUITIES OF THE CITY OF fcONDON, 



.'!iu — H;iving been calleil in by the Rector of Saint Mary .Alder- 

 man/ and Saint Thomas the Apostle, to inspect the North Wall of the 

 Church of Saint Mary Aklermary, WatUng-stroet, I was led to the 

 follow iug conclusion, after a most careful examination, as to tlie anti- 

 quity of jjortions of that wall, which may prove interesting to many of 

 your readers. 



In rebuilding the church after the memorable fire of London, it 

 seems that Sir Christopher Wren not only retained the original line of 

 the north wall, but finding it unnecessary to puU it down entirely, left 

 it untouched as far up as a string-course which formerly ran along the 

 whole length of the church, under the sills of the windows of the north 

 aisle, traces of it being perfectly discernible to an eye familiar with 

 the remains of antiquity, from the north-east angle of the building to 

 the north doorwaj'. There are also remains of the original basement- 

 moulding, and the original buttresses still exist with the stringcourse 

 profiled round them, they are five in number, and, in one or two places, 

 the face of their ashlar is as perfect as when first worked. The 

 original ashlar of the whole of this wall still remains from the level of 

 the ground to that of the string-course before mentioned, and indeed 

 a small portion of it is left some five or six feet above the string- 

 course, immediately adjoining the easternmost buttress. The re- 

 building is clearly defined by the rough masonry of this wall above the 

 level of the string-course, which seems to have been intended at the 

 time ;is a party-wall between the church ami the glebe-houses, not 

 only on account of its not being faced, but also on account of the entire 

 absence of openings for light. The north doorway, with its discharging 

 arch in rough masonry is evidently an insertion in the original wall, 

 the recesses over the doorway seem to have bceii left as cupboards for 

 the adjoining house, as the masonry of their arches is coeval w ith that 

 of the discharging arch over the doorway. Before the fire, I have no 

 doubt, this wall was quite unincumbered by buildings, first, because 

 the ashlar still remaining shows a fair face; secondly, because the 

 buttresses still exist, showing also a fair face; and thirdly, because 

 remains of the basement-moulding and the string-course, both being 

 exterior features, can be clearly pointed out. There nmst therefore 

 have been a space, originally, betw een the church anil the glebe, which 

 seems to have been used as a burial-place, as human bones were some 

 years ago found near the footing of tliis wall. This space, on account 

 of Watling-street having been either widened at the time or removeil 

 farther southwards, (212i feet were cut oft" from the glebe land in 

 front towards the street, see Oliver's Survey, vol. -2, p. 155,1 was, by 

 the Decrees of the Judges, made part and parcel of the glebe ; and 

 this accounts satisfactorily for that wall having been, in the rebuilding, 

 made a party-wall, and also for the right of way having been reserveil 

 to the parishioners from the street, through the glebe, up to the north 

 doorway of the church. 



I have made a careful drawing of these remains, which I shall be 

 most happy to show to any one who, like myself, may take an interest 

 in old gotliic buildings. 



Youi-'s, &c., 



Thos. E. Walker. 



2, Keppel-street, Russell-square, Dec. 3, 1839. 



ISLE OF SHEPPY. 

 S[R — Having read an extract from the Cincpie Ports Chronicle in 

 this mouth's journal, on "The Encroachments and Recessions of the 

 Sea," in which the only reason assigneil for the former is the action of 

 the sea in its ceaseless beatings against the shore ; I am induced to 

 bring to your notice the Isle of Sheppy, where from another cause the 

 sea is making a more rapid encroachment than perhaps any other part 

 of England : so much so, tliat I think in a very few years the greater 

 part of Minster Hill, the Station Houses at East End Lane, and Hens- 

 broche will be swalloweil up by the sea. Indeed the extent of bank 

 left at low water, particularly during spring tides, and the very great 

 ilistanoe from the beach that the stone for cement is dug up, (1 be- 

 licve the Rudis Helmontia) prove that the island was once of much 

 greater extent than at present, and from my observation of the land 

 slips that have taken place since I came here in Juno last, I should 

 certainly say they were caused by underground springs endeavouring 

 to find an outlet, and that by proper drainage much valuable land 

 might be sa\ed. Indeed the shelving beach or strand caused by the 

 former destruction of the island is now a strong natural protection to 

 it, and that the present almost daily loss is owing to want of care in 

 directing the numerous springs into a proper channel. 

 I am. Sir, your obedient servant, 



C. F. Parkinson. 

 Captain 73rd Regiment. 



STEAM BO.\T PROPELLERS. 



Eijieriments by Georye Rennie, Esq., communicated to the Editor of tlie 

 Railway Magazine. 



I HEREWITH send you the average result of a series of experiments I have 

 made on the comparative merits of several instruments wliicli have i)ecn tried 

 for propelling vessels through water, mider similar circiuustances. In order, 

 therefore, to arrive .it this knowledge, three diftereut sets of experiments 

 were tried : first, on a model wheel, of two feet in diameter, fixed in a trough 

 of water, and moved by a weight falling through equal height ; secondly, by 

 means of a boat to which the ditTerent kinds of ])ropcl!er were adapted, so as 

 to render the circumstances sinular in even,- respect; thirdly, by means of a 

 small steamer, of moderate dimensions, so as to enable the experiments to be 

 made in still water, and tluis obtain more accurate results than could possibly 

 be obtained in a tidal river like the Thames. The following are the results 

 on the model — 



An experiment was then tried by immersing the rectangular floats to twice 

 their depth. The result was to increase the time of the 41b. weight falling 

 to 32 seconds, ordoul)le the resistance when immersed to the ordiu.ary depth 

 of the float, while tlie trapezium-shaped float, doubly immersed, only required 

 IG seconds for tjie 41b. weight to fall through the same space ; thus, proving 

 the great defect of the paddle-wheel, .as apphedto all sea-going steam-vessels, 

 so that when deeply laden with coals at the first part of their voyages, the 

 engines can only make half their proper number of strokes. The Ilritish 

 Qireen, for instance, the engines of which are frequently reduceil to nine, in- 

 stead of seventeen or eighteen, the full number of strokes. These experi- 

 ments have been repeated again and again, before competent witnesses, and 

 always with the same results. 



Secondly— with dittercnt kinds of propellers attached to the same boat. 



The following are the comparative results i — 



Tntjle ill which are compared tlie Performances of the Screw. Propeller, 

 Conoidal'Propeller, and Paddle-wheeh. 



N.B. — The above experiments were made with a boat such as is used in 

 the whale fisheiT; its length was 27 feet, its breadth 5 feet, its depth 2 feet 

 1 inch, and its weight, with ballast and persons on board, 2828 lbs., the area 



E 



